Adenoviruses (Ad) represent a major cause of viral conjunctivitis in man. Although usually self-limiting, Ad ocular infections have a high level of infectivity and transmission rate causing significant morbidity and socioeconomic problems due to numerous lost working days each year. Immune responses occurring during ocular infections can also lead to severe visual disturbances including blindness. Antiviral strategies aimed at blocking virus entry into cells have been relatively underdeveloped due to a lack of knowledge of the precise viral and cellular components that mediate the entry events. The cell surface integrins alpha-v-beta3 and alpha-v-beta5 mediate adenovirus internalization rather than virus attachment via a specific interaction with an RGD sequence in the virus penton base capsid protein. Moreover, our recent studies indicate that integrins alpha-M-beta2 and alpha-L- beta2 promote adenovirus attachment to human monocytic and lymphoid cells. This proposal seeks to capitalize on these findings to develop a rational approach to blocking adenovirus ocular infections in vivo. Since several different adenovirus serotypes use alpha-v integrins for infection, the use of potent antagonists of these receptors may confer protection against multiple virus serotypes. A series of detailed molecular and biochemical studies will be used to elucidate the precise interactions of Ad penton base with distinct cell integrins in order to gain further insights into adenovirus cell entry. The kinetics, thermodynamics and stoichiometry of penton base binding to cell integrins will be determined using an automated biosensor system. The precise amino acid sequences in the penton base that mediate binding to different cell integrins will be identified by analyzing peptide binding to immobilized integrins using laser- desorption mass spectrometry. A second goal of the proposal is to determine the overall role of beta2 integrins in adenovirus infection of human monocyte/macrophages and lymphocytes, two cell types that contribute to Ad ocular pathogenesis. These cells are also a likely site for persistent Ad infection in the host. Finally, a potent synthetic peptide antagonist of cell integrins or a function-blocking monoclonal antibody that recognizes the RGD domain of multiple adenovirus serotypes will be used to prevent adenovirus infection in the NZW rabbit ocular model. These studies represent a rational approach to block Ad ocular infection in vivo and may also lead to improved strategies for using replication-defective adenovirus vectors for ocular gene therapy.